📌 MySQL WHERE Clause – Syntax, Filters, Operators & Examples

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🧲 Introduction – Why Learn the WHERE Clause?

The WHERE clause is a vital part of the SQL language, especially in MySQL. It allows you to filter records from a table based on specified conditions. Whether you’re pulling customer data from a specific country or getting sales data from a particular date range, the WHERE clause is essential for targeted data retrieval.

🎯 In this tutorial, you’ll learn:

• Syntax and structure of the WHERE clause in MySQL
• How to use comparison and logical operators
• Advanced filtering using IN, BETWEEN, LIKE, and IS NULL
• Real-world examples of filtering data

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📘 What is the WHERE Clause in MySQL?

The WHERE clause is used to specify conditions for filtering records in SELECT, UPDATE, DELETE, and INSERT statements.

✅ Basic Syntax:

SELECT column1, column2, ...
FROM table_name
WHERE condition;

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🧪 Examples of MySQL WHERE Clause

🔹 Example 1: Filter by Exact Match

SELECT * FROM customers
WHERE country = 'India';

📌 Returns only customers from India.

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🔹 Example 2: Filter with Numeric Condition

SELECT * FROM products
WHERE price > 500;

📌 Shows products priced above 500.

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🔹 Example 3: Filter Multiple Conditions with AND

SELECT * FROM orders
WHERE status = 'shipped' AND payment_method = 'credit card';

📌 Returns orders that are shipped and paid by credit card.

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🔹 Example 4: Filter Using OR

SELECT * FROM users
WHERE city = 'Mumbai' OR city = 'Delhi';

📌 Retrieves users from either Mumbai or Delhi.

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🔹 Example 5: Use of NOT Operator

SELECT * FROM employees
WHERE NOT department = 'HR';

📌 Excludes records where the department is HR.

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🧠 Advanced Filtering Techniques

🔹 Using BETWEEN for Range Queries

SELECT * FROM transactions
WHERE amount BETWEEN 1000 AND 5000;

📌 Fetches records where the amount is within the given range.

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🔹 Using IN for Multiple Values

SELECT * FROM orders
WHERE status IN ('pending', 'shipped', 'delivered');

📌 Matches any of the listed statuses.

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🔹 Using LIKE for Pattern Matching

SELECT * FROM customers
WHERE name LIKE 'A%';

📌 Returns customers whose names start with “A”.

SELECT * FROM customers
WHERE email LIKE '%@gmail.com';

📌 Returns customers with Gmail addresses.

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🔹 Using IS NULL or IS NOT NULL

SELECT * FROM payments
WHERE discount IS NULL;

📌 Filters rows where the discount column has no value.

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⚖️ WHERE Clause Operators Summary

Operator	Description	Example
=	Equal to	WHERE age = 30
!= / <>	Not equal to	WHERE status != 'inactive'
> / <	Greater/Less than	WHERE salary > 50000
>= / <=	Greater/Less than or equal to	WHERE marks >= 60
BETWEEN	Range (inclusive)	WHERE age BETWEEN 20 AND 30
IN	Match any value in a list	WHERE city IN ('Delhi', 'Pune')
LIKE	Pattern matching	WHERE name LIKE 'S%'
IS NULL	Check for NULL	WHERE address IS NULL

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🛠️ WHERE Clause Use Cases in MySQL

Scenario	SQL Example
🎯 Find customers in a city	SELECT * FROM customers WHERE city = 'Bangalore';
🛍️ Get orders above ₹10,000	SELECT * FROM orders WHERE total > 10000;
🔐 Validate login info	SELECT * FROM users WHERE email = 'admin@xyz.com' AND password = 'abc123';
📅 Check for date ranges	SELECT * FROM logs WHERE login_date BETWEEN '2024-01-01' AND '2024-12-31';

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📌 Summary – Recap & Next Steps

The WHERE clause enables precision in your MySQL queries. It narrows down results, making queries efficient and meaningful.

🔍 Key Takeaways

• Use WHERE with SELECT, UPDATE, DELETE, and INSERT
• Combine with logical operators (AND, OR, NOT)
• Supports advanced filters: IN, BETWEEN, LIKE, IS NULL
• Makes your queries targeted and efficient

⚙️ Real-World Relevance

From filtering out inactive users to querying high-value orders, the WHERE clause is the core of decision-making in SQL.

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❓ FAQ – MySQL WHERE Clause

❓ Can I use WHERE with multiple conditions?

✅ Yes, combine them using AND, OR, and parentheses.

❓ What’s the difference between = and IN?

✅ = checks for a single match, while IN checks multiple:

WHERE city = 'Delhi'          -- Single
WHERE city IN ('Delhi','Pune') -- Multiple

❓ How do I use WHERE with dates?

✅ Use the standard format 'YYYY-MM-DD':

WHERE order_date = '2025-05-01'

❓ Can I use WHERE with NULL values?

✅ Yes. Use IS NULL or IS NOT NULL:

WHERE email IS NOT NULL;

❓ What happens if I forget the WHERE clause in UPDATE or DELETE?

⚠️ It will affect all rows in the table! Always double-check.

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